For typical gas distribution systems, the supplied pressure may vary according to the demands placed on the system, the climate, the source of supply, and/or other factors. However, most end-user facilities equipped with gas appliances such as furnaces, ovens, etc., require the gas to be delivered in accordance with a predetermined pressure, and at or below a maximum capacity of a fluid regulator. Therefore, fluid regulators are implemented in these distribution systems in order to ensure that the delivered gas meets the requirements of the end-user facilities.
Fluid regulators, which regulate the fluid pressure and/or flow to maintain a selected output pressure, are generally well known in the art. One type of fluid regulator is a single stage pressure regulator, which acts to reduce the incoming or source pressure to the outlet or delivery pressure in a single step. Another type of fluid regulator is a dual stage regulator, which reduces the inlet pressure to the outlet pressure in two steps. A known dual stage fluid regulator 10 is illustrated in FIG. 1. The fluid regulator 10 includes a regulator body 12 defining a fluid inlet 14 and a fluid outlet 16 connected by a fluid flow path 18 that extends generally through the body 12. The fluid regulator 10 is generally divided into a number of chambers, including a first chamber 20, a second chamber 22, and a third chamber 24. The fluid regulator 10 includes a first stage orifice 26 disposed in the fluid flow path 18 and leading to a first stage seat 28, and a second stage orifice 30 disposed in the fluid flow path 18 and leading to a second stage seat 32. A first stage control element 34 is disposed within the fluid flow path 18 and is shiftable between an open position (as shown in FIG. 1) in which the first stage control element 34 is spaced away from the first stage seat 28, and a closed position in which the first stage control element 34 is seated against the first stage seat 28. The fluid regulator 10 includes an actuator 36 which is attached to the regulator body 12. The actuator 36 is attached to or otherwise operatively coupled to the first stage control element 34, and is arranged to respond to fluid pressure changes in the fluid outlet 16 and to move the first stage control element 34 between the open position and the closed position in order to control the flow of the process fluid through the first stage orifice 26. The actuator 36 may be conventional, and moves a lever 38 operatively coupled to the first stage control element 34 in order to open or close the first stage control element 34, depending on pressure conditions in the third chamber 24. The actuator 36 includes a diaphragm, load springs, and a suitable stem or other suitable linkage as would be known. A second stage control element 40 is disposed within the fluid flow path 18 and is shiftable between an open position (as shown in FIG. 1) in which the second stage control element 40 is spaced away from the second stage seat 32, and a closed position in which the second stage control element 40 is seated against the second stage seat 32 (in which the control element 40 would be positioned to the left of the open position of FIG. 1). The second stage control element 40 is arranged to respond to fluid pressure changes and to control flow of a process fluid through the second stage orifice 30.
In operation, the inlet 14 is exposed to a supply pressure Pi, while the outlet 16 is exposed to an outlet or operating pressure P0, which is the operating pressure required by the devices located downstream requiring gas at the lower operating pressure. The inlet pressure Pi is higher than the outlet or operating pressure P0. The first chamber 20 is in flow communication with a vent 42 to atmosphere, and consequently the first chamber 20 is at atmospheric pressure Pa. The second chamber 22 is typically at a middle pressure Pm between the inlet pressure Pi and the outlet pressure P0. During operation, the inlet pressure Pi is typically sufficiently high to keep the second stage control element 40 in the open position as shown in FIG. 1. If the inlet pressure Pi drops sufficiently, then the pressure within the second chamber 22 causes the second stage control element 40 to shift to the left toward, or to, the closed position, closing the second stage. Operation of the first stage is also conventional. When the pressure in the third chamber 24 drops, meaning pressure at the gas devices downstream has dropped, the load springs in the actuator 36, which load springs bear against a diaphragm of the actuator 36, overcome the gas pressure against the diaphragm. Consequently, the actuator 36 moves the stem and/or diaphragm plate downward, rotating the lever 38 in a downward direction to move the first stage control element 34 away from the seat 32, feeding additional gas into the third chamber 24. Conversely, when the pressure in the third chamber 24 increases, the actuator causes the first stage control element 34 to move toward, or to, the seat 28, lowering the pressure in the third chamber 24.
As illustrated in FIG. 1, the lever 38 is secured to the regulator body 12 by a pin 44 and is operatively coupled to the first control element 34 and the actuator 36. The pin 44 is disposed within a cavity formed in the regulator body 12 such that the walls of the cavity limit the translational movement of the pin 44. The lever 38 is generally attached to the regulator body 12 by the pin 44 at a front end and freely rotates about the pin 44 when the actuator 36 moves the lever 38 in a vertical direction at a back end. Upon downward vertical movement of the back end, the lever 38 rotates about the pin 44 and pulls the control element 34 in the direction of flow 18 and away from the first seat 28. The positioning of the lever 38 may be carefully calibrated such that when the actuator 36 moves the lever 38 in a vertical direction, the lever rotates relative to the pin 44, causing the control element 34 to move away from or toward the first stage seat 28 a predetermined distance. The lever 38 and the pin 44 are rotatably connected, i.e. the lever 38 and the pin 44 rotate relative to each other and share a common axis of rotation. The pin 44 is rotatably connected to the lever 38 at an aperture having enough clearance for a loose fit allowing the lever 38 to rotate and slide freely along the pin 44. In a highly pressurized environment, the lever 38 may become loose and may swing in a horizontal direction relative to the axis of the pin, creating a flutter.
The lever 38 and the pin 44 provide an important function of operatively coupling the actuator 36 with the control element 34. The lever 38 rotates about the pin 44, converting vertical movement of the actuator 36 to translational movement of the control element 34. Each of the vertical movement of the actuator 36, rotation of the lever 38, and translational movement of the control element 34 is predetermined for the actuator 36 to accurately respond to outlet pressure and to control the flow of fluid through the first stage orifice 26. In a fluid regulator 10, high pressurized fluids (liquids or gases) flow through the fluid flow path 18 and may move the lever 38 independently from the pin 44. Even slight deviations from the predetermined actions of the actuator 36 and the control element 34 (caused by the additional movements of the lever 38) may significantly disrupt the flow of process fluid through the regulator 10. For example, frequent or repetitive lever movements and flutter create wasted motion and may gradually wear the coupling surfaces of the pin 44 and the lever 36, the coupling surfaces of the lever 38 and the control element 34, the coupling surfaces of the lever 38 and the actuator 36, and other mechanical parts within the regulator 10. The lever flutter and horizontal swing may negatively affect the responsiveness and/or accuracy of the lever 38 to the vertical movement of the actuator 36, and thereby the responsiveness and/or accuracy of the control element 34 to the rotation of the lever 38. As a result, the control element 34 may unexpectedly move away or toward the stage seat 32 or become unresponsive to the movements of the actuator 36, leading to inaccuracy, inconsistent flow capacities, instability, slow response time, expedited system wear, and system failure. Accordingly, it may be desirable to provide a fluid regulator exhibiting reduced or minimized adverse effects due to environmental and/or mechanical factors.